http://www.reddit.com/r/arizona/comments/2atxve/someone_has_been_sharpening_rebar_and_driving_it/

Some <img src="/forums/images/graemlins/butwiggle.gif" alt="" /> [Linked Image] has been putting rebar spikes in the ground on OHV trails, to sabotage tires.

If you see something like that, pull it out of the ground and call the police.